Do I have anything to worry about here?

So I'm a seller of various bits and bobs on eBay. I sold a Blu-ray movie to some guy (to elsewhere in the UK). I sent it out at the Post Office, via regular post but crucially I got a reference number upon dispatch (thankfully this came with a delivery confirmation; it wasn't tracked 'all the way' but presumably it had a requirement to be scanned by the Postie when it was due to be delivered as part of the process).

So a few days go by, and the buyer has been in touch and has opened a case with eBay for IND. The thing is, the delivery confirmation has confirmed that the package has been delivered, and on the tracking there was even an option to type in the recipient's post code and a little GPS image has come up on my screen to show where the package has been delivered to. Do I have anything to worry about in terms of the buyer potentially being 'awarded' a refund? Even though the tracking suggests that the item has in fact been delivered? Is the buyer who is presumably 'trying to pull a fast one' likely to get any sort of compensation from eBay? Thank you all